The abyssal dagger is the most powerful dagger in the game requiring 70 Attack to wield. Players have a 13/64 (20.313%) chance of receiving an abyssal dagger when using an unsired on the Font of Consumption at the centre of the Abyssal Nexus, giving it effectively a chance of 1/492 (0.203%) per Abyssal Sire kill. Players also have a 1/32,768 (0.003%) chance of receiving an abyssal dagger as a drop from abyssal demons.

The abyssal dagger surpasses the staff of the dead in both Strength and accuracy, with +5 Attack bonus, and +3 Strength bonus. Players should note that the abyssal dagger is primarily a stab weapon while the staff of the dead is primarily a slash weapon. The Zamorakian hasta surpasses the abyssal dagger as a stab weapon with its prayer bonus, defensive stats, and additional stab attack bonus, but many players choose not to use it due to its combat styles being limited to defensive and controlled (shared).

A player performs the abyssal dagger's special attack, Abyssal Puncture.

The abyssal dagger has a special attack, Abyssal Puncture, which hits twice in quick succession with a 25% increase in accuracy and 15% reduced damage, consuming 50% of the player's special attack energy. The special attack's first hit must deal damage for the second hit to deal damage.

The highest the dagger can possibly hit with its special attack is 40-40 against players and 46-46 while using a salve amulet (e) against undead creatures. The abyssal dagger's special attack is arguably significantly weaker than the dragon dagger's; this is evident when comparing the abyssal dagger's max hit of 40-40 which uses 50% special attack energy to the dragon dagger's max hit of 46-46 which uses 25% special attack energy.